Expansion assembly for a tubular expander tool, and method of tubular expansion

ABSTRACT

An improved expansion assembly for an expander tool is provided, and a method for expanding a surrounding tubular body within a wellbore. The expansion assembly first comprises a piston disposed within a recess of the expander tool. The top surface of the piston closely receives a body. The bearing body includes one or more races which house at least one bearing. In one arrangement, at least one bearing is provided which rotationally resides within a single race. In another arrangement, a plurality of bearings are provided that recirculate within one or more races. In this arrangement, the bearing body is preferably a tapered, cylindrical roller actuated into contact with the surrounding tubular by hydraulic pressure applied from within the bore of the expander tool. These arrangements reduce the geometric size of the expansion assembly, affording a larger inner diameter for the hollow bore of the expander tool itself.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to wellbore completion. More particularly, the invention relates to an apparatus and method for expanding a tubular body. More particularly still, the apparatus relates to an expander tool for expanding a section of tubulars within a wellbore.

[0003] 2. Description of the Related Art

[0004] Hydrocarbon and other wells are completed by forming a borehole in the earth and then lining the borehole with steel pipe or casing to form a wellbore. After a section of wellbore is formed by drilling, a string of casing is lowered into the wellbore and temporarily hung therein from the surface of the well. Using apparatus known in the art, the casing is cemented into the wellbore by circulating cement into the annular area defined between the outer wall of the casing and the borehole. The combination of cement and casing strengthens the wellbore and facilitates the isolation of certain areas of the formation behind the casing for the production of hydrocarbons.

[0005] It is common to employ more than one string of casing in a wellbore. In this respect, a first string of casing is set in the wellbore when the well is drilled to a first designated depth. The first string of casing is hung from the surface, and then cement is circulated into the annulus behind the casing. The well is then drilled to a second designated depth, and a second string of casing, or liner, is run into the well. The second string is set at a depth such that the upper portion of the second string of casing overlaps the lower portion of the first string of casing. The second liner string is then fixed or “hung” off of the existing casing by the use of slips which utilize slip members and cones to wedgingly fix the new string of liner in the wellbore. The second casing string is then cemented. This process is typically repeated with additional casing strings until the well has been drilled to total depth. In this manner, wells are typically formed with two or more strings of casing of an ever decreasing diameter.

[0006] Apparatus and methods are emerging that permit tubular bodies to be expanded within a wellbore. The apparatus typically includes an expander tool that is run into the wellbore on a working string. The expander tool includes radially expandable members, or “expansion assemblies,” which are urged radially outward from a body of the expander tool, either in response to mechanical forces, or in response to fluid injected into the working string. The expansion assemblies are expanded into contact with a surrounding tubular body. Outward force applied by the expansion assemblies cause the surrounding tubular to be expanded. Rotation of the expander tool, in turn, creates a radial expansion of the tubular.

[0007] Multiple uses for expandable tubulars are being discovered. For example, an intermediate string of casing can be hung off of a string of surface casing by expanding an upper portion of the intermediate casing string into frictional contact with the lower portion of surface casing therearound. Additionally, a sand screen can be expanded into contact with a surrounding formation in order to enlarge the inner diameter of the wellbore. Additional applications for the expansion of downhole tubulars exist.

[0008] An exemplary embodiment of an expander tool previously known as of the filing of this continuation-in-part application is shown in FIG. 1. FIG. 1 is an exploded view of an exemplary expander tool 100. FIG. 2 presents the same expander tool 100 in cross-section, with the view taken across line 2-2 of FIG. 1.

[0009] The expander tool 100 has a body 102 which is hollow and generally tubular. The central body 102 has a plurality of recesses 114 to hold a respective expansion assembly 110. Each of the recesses 114 has substantially parallel sides and holds a respective piston 120. The pistons 120 are radially slidable, one piston 120 being slidably sealed within each recess 114. The back side of each piston 120 is exposed to the pressure of fluid within a hollow bore 115 of the expander tool 100. In this manner, pressurized fluid provided from the surface of the well can actuate the pistons 120 and cause them to extend outwardly.

[0010] Disposed above each piston 120 is a roller 116. In one embodiment of the expander tool 100, the rollers 116 are near cylindrical and slightly barreled. Each of the rollers 116 is supported by a shaft 118 at each end of the respective roller 116 for rotation about a respective axis. The rollers 116 are generally parallel to the longitudinal axis of the tool 100. In the arrangement of FIG. 1, the plurality of rollers 116 is radially offset at mutual 120-degree circumferential separations around the central body 102. In the arrangement shown in FIG. 1, two offset rows of rollers 116 are shown. However, only one row, or more than two rows of roller 116, may be incorporated into the body 102.

[0011] As sufficient pressure is generated on the bottom piston surface behind the expansion assembly 110, the tubular being acted upon (not shown) by the expander tool 110 is expanded past its point of elastic deformation. In this manner, the diameter of the tubular is increased within the wellbore. By rotating the expander tool 100 in the wellbore and/or moving the expander tool 100 axially in the wellbore with the expansion assemblies 110 actuated, a tubular can be expanded into plastic deformation along a predetermined length. Where the expander tool 100 is translated within the wellbore, the shaft 118 serves as a thrust bearing.

[0012] One disadvantage to known expander tools, such as the hydraulic tool 100 shown in FIGS. 1-2, is the inherently restricted size of the hollow bore 115. In this respect, the dimension of the bore 115 is limited by the size of the expansion assemblies 110 radially disposed around the body 102 of the tool 100. The constricted bore 115 size, in turn, imposes a limitation on the volume of fluid that can be injected through the working string at any given pressure. Further, the dimension of the bore 115 in known expander tools places a limit on the types of other tools which can be dropped through the expander tool 100. Examples of such tools include balls, darts, retrieving instruments, fishing tools, bridge plugs and other common wellbore completion tools.

[0013] In addition, the tubulars being expanded within a wellbore generally define a thick-walled, high-strength steel body. To effectively expand such tubulars, a large cross-sectional geometry is required for the roller body 116. This further limits the inner bore diameter, thereby preventing adequate flow rates, and minimizing the space available to run equipment through the inner bore 115. Also, the stresses required to expand the material are very high; hence, reducing the roller body size to accommodate a larger inner bore diameter would mechanically weaken the roller mechanism, thereby compromising the functionality of the expansion assembly.

[0014] Therefore, a need exists for an expander tool which provides for a larger configuration for the hollow bore 115 therein. Further, a need exists for an expander tool which reduces the size of the expansion assemblies 110 around the tool 100 so as to allow for a greater bore 115 size without reducing the size of the roller body. Further, a need exists for an expander tool having expansion assemblies which do not rely upon rollers 116 rotating about a shaft 118 at a spaced apart distance from the piston member 120.

SUMMARY OF THE INVENTION

[0015] The present invention provides an apparatus for expanding a surrounding tubular body. More specifically, an improved expansion assembly for a radially rotated expander tool is disclosed. In addition, a method for expanding a tubular body, such as a string of casing within a hydrocarbon wellbore, is provided, which employs the improved expansion assembly of the present invention.

[0016] The expansion assembly first comprises a piston. The piston is preferably an elongated wafer-shaped body which is sealingly disposed within an appropriately configured recess of an expander tool. The piston has a top surface and a bottom surface. The top surface is configured to receive a bearing body. In the expansion assembly of the present invention, the bearing body preferably is not a roller body, and does not rotate about a shaft; instead, the bearing body resides in close proximity to the top surface of the piston. This reduces the overall size of the expansion assembly, allowing more room for the hollow bore within the expander tool.

[0017] To aid in rotation of the expansion assembly, the bearing body includes one or more bearings along the roller body surface. In one embodiment, a plurality of recirculating bearings are employed. The bearings are preferably spherical in shape, and are held within a plurality of races arranged in rows. The races are sized to permit the bearings to recirculate therein.

[0018] In one aspect, the top surface of the piston includes a series of grooves, or “scallops,” that correspond to the races in the bearing body. The scalloped surface allows the bearing body to rest immediately upon the top surface of the piston, with the scallops receiving the bearings as they recirculate.

[0019] In another embodiment, a single bearing is disposed within the bearing body. The bearing is preferably spherical in shape, and resides within a single race in the bearing body. The single race is sized to permit the ball to freely rotate as it engages a surrounding tubular.

[0020] Where a plurality of bearings is employed, the bearing body is preferably tapered. This more easily allows the expander tool to both rotate and translate within the wellbore simultaneously. The bearing body is mounted onto the top surface of the piston. In one aspect, mounting is by brackets affixed to the top surface of the piston at opposite ends. The brackets receive connectors that connect the bearing body to the brackets. In this way, the bearing body resides intermediate the two opposite brackets.

[0021] In one arrangement, the bottom surface of the piston is exposed to fluid pressure within the bore of the expander tool. The piston is moved radially outward from the body of the expander tool but within the recess in response to fluid pressure or other outward force within the bore. Because the bearing body is held closely to the piston, greater space is accommodated for the bore within the expander tool.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] So that the manner in which the above-recited features of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the appended drawings (FIGS. 3-14). It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

[0023]FIG. 1 is an exploded view of an expander tool previously known as of the time of the filing of this continuation-in-part application. The roller is consistent with an embodiment described in the pending parent application. Visible in FIG. 1 is an expansion assembly having a roller which rotates about a shaft.

[0024]FIG. 2 is a cross-sectional view of the expander tool of FIG. 1, taken across line 2-2 of FIG. 1.

[0025]FIG. 3 is an exploded view of an expansion assembly of the present invention, in one embodiment. The expansion assembly is shown in perspective view. The expansion assembly is designed to operate within a body of an expander tool, such as a hydraulically actuated expander tool.

[0026]FIG. 4 is a side, cross-sectional view of the expansion assembly of FIG. 3.

[0027]FIG. 5 is a top view of the expansion assembly of FIG. 3.

[0028]FIG. 6 is an exploded view of an expander tool which includes expansion assemblies of the present invention.

[0029]FIG. 7 is a cross-sectional view of the expander tool of FIG. 6, taken across line 7-7 of FIG. 6.

[0030]FIG. 8 is an exploded view of an alternate embodiment of an expansion assembly. In this arrangement, a single bearing is employed. The assembly is exploded from an expander tool.

[0031]FIG. 9 is a cross-sectional view of the expander tool of FIG. 8, taken across line 9-9 of FIG. 8. A single bearing is shown residing on the top surface of each piston.

[0032]FIG. 10A is a cross-sectional view of the expansion assembly of FIG. 8, taken across a line perpendicular to the longitudinal axis of the expansion assembly. FIG. 10B is a cross-sectional view of the expansion assembly of FIG. 8, taken across the longitudinal axis of the expansion assembly.

[0033]FIG. 11 is a cross-sectional view of a wellbore. The wellbore includes an upper string of casing, and a lower string of casing having been hung off of the upper string of casing. In this view, the lower string of casing serves as a tubular body to be expanded.

[0034]FIG. 12 presents the wellbore of FIG. 11. In the view, an expander tool which includes expansion assemblies of the present invention is being lowered into the wellbore on a working string.

[0035]FIG. 13 presents the wellbore of FIG. 11, with the expander tool being actuated in order to expand the lower string of casing into the upper string of casing, thereby further hanging the liner from the upper string of casing.

[0036]FIG. 14 presents the wellbore of FIG. 13, in which the lower string of casing has been expanded into the upper string of casing along a desired length. The expander tool is being removed from the wellbore.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0037]FIG. 3 presents a perspective view of an expansion assembly 210 of the present invention, in one embodiment. The expansion assembly 210 is designed to be utilized within an expander tool (shown in FIG. 6) for expanding a surrounding tubular body (demonstrated in FIGS. 12-14). The parts of the expansion assembly 210 are presented in an exploded view for ease of reference.

[0038] The expansion assembly 210 first comprises a piston 220. As will be discussed, the piston 220 resides within a recess of an expander tool 200. In the arrangement shown in FIG. 3, the piston 220 defines an elongated, wafer-shaped member capable of sliding outwardly from the expander tool in response to hydraulic pressure within the bore 215 of the expander tool 200. A piston body recess 223 is circumferentially formed around the piston 220 in order to receive a seal (not shown).

[0039] The piston 220 has a top surface and a bottom surface. The bottom surface is exposed to hydraulic pressure within the bore 215 of the expander tool 200. The top surface of the piston 220 is configured to receive a bearing body 216. In the expansion assembly of the present invention, the bearing body 216 does not rotate about a shaft; instead, the bearing body 216 fixedly resides in close proximity to the top surface of the piston 220. In the arrangement of FIG. 3, the bearing body 216 does not roll or skid along the top surface of the piston 220.

[0040] To aid in rotation of the expander tool 200 with the expansion assemblies 210, the bearing body 216 includes a plurality of bearings 218 along the body surface. The bearings 218 are preferably spherical in shape, but may also be cylindrical or egg-shaped. The bearings 218 are held within a plurality of races 214 arranged in rows. The races 214 are sized to permit the bearings 218 to recirculate therein.

[0041] In the arrangement shown in FIGS. 3 and 5, the races 214 are arranged in a plurality of parallel rows. Five separate, parallel rows are provided. However, it is within the scope of the present invention to employ additional or fewer rows, so long as the bearing body 216 is able to effectively expand a surrounding tubular body. In this respect, it is the bearings 218 that provide the primary engagement between the expander tool 200 and the surrounding tubular during an expansion operation. In addition, it is within the spirit of this invention to utilize any configuration of races 214, such as a nonlinear or a nonparallel arrangement (not shown).

[0042] It is preferred that a hardened substrate be fabricated into the bearing body 216 along the races 214. A material of appreciable strength and toughness is employed such that the high hertzian stresses applied during an expansion operation do not detrimentally deform the races 214. Examples include ceramics and tungsten carbide.

[0043] The bearing body 216 is mounted onto the top surface of the piston 220. Any mounting arrangement may be employed. In the embodiment shown in FIG. 3, a pair of brackets 230 a, 230 b is affixed to the top surface of the piston 220 at opposite ends of the piston 220 a, 220 b. The brackets 230 a, 230 b receive respective connectors 232 a, 232 b that connect the bearing body 216 to the brackets 230 a, 230 b. One or more bolts 250 is provided to secure each connector 232 a, 232 b to its corresponding bracket 230 a, 230 b. The body 216, brackets 230 a, 230 b and connectors 232 a, 232 b may be of a unitary construction with the piston 220, or may be separate pieces as shown in FIG. 3. In any of such arrangements, the bearing body 216 preferably resides and remains rotationally fixed intermediate the two opposite brackets 230 a, 230 b.

[0044] In the arrangement of FIG. 3, each connector 232 a, 232 b includes a plate 236 and a tongue 234. The tongue 234 defines an elongated, substantially flat member that extends into a recess 236 within the bearing body 216 at an end. The tongue 234 aids in stabilizing the bearing body 216 relative to the piston 220. The tongue 234 is best shown in the exploded view of FIG. 3. In this view, it can be seen that the tongue 234 does not serve as an axle so that the bearing body 216 in the expansion assembly 210 does not significantly rotate relative to the piston 220. Removal of the shaft 118 from the previous embodiment of an expansion assembly 110 (FIG. 1) allows the overall diameter of the body 202 of the new expander tool 200 (shown in FIG. 6) to be increased, thereby saving valuable space within the bore 215 of the expander tool 200.

[0045] In an alternative embodiment, the body 216 is arranged to rotate as with the roller body of the prior art, thereby providing an additional rotation means to the tool. In such an arrangement, a swivel connection (not shown) is preferably provided between the brackets 230 a, 230 b and the body 216.

[0046] To further aid in the space-saving function of the expansion assembly 210, the bearing body 216 is disposed immediately upon the top surface of the piston 220. To accommodate the integral bearing mechanism defined by the bearings 218, “scallops” 226 are fabricated into the piston 220. In FIGS. 3-5, the scallops 226 are shown along the top surface of the piston 220. Each scallop 226 defines a groove that is sized and configured to correspond to a race 214 along the bearing body 216. The scalloped piston surface 220 allows the bearing body 216 to rest immediately upon the top surface of the piston 220, with the scallops 226 receiving the bearings 218 and permitting recirculation thereof.

[0047] The configuration of the roller 116 shown in the prior art drawing of FIG. 1 is somewhat barrel-shaped. It also has a cross-sectional shape that is generally cylindrical. Such a configuration may be used in the bearing body 216 for the improved expansion assembly 210 of the present invention. Of course, it is to be appreciated that other roller shapes may be used, including semi-spherical, multifaceted, elliptical or any other cross sectional shape suited to the expansion operation to be conducted within a tubular. However, to further aid in the space-saving function of the expansion assembly 210, a tapered eccentric (non-circular) bearing body 216 shape is provided, as shown in FIG. 3.

[0048] The configuration of the novel bearing body 216 is best seen in the side cross-sectional view of FIG. 4. The surface of the bearing body 216 proximate to the piston 220 is essentially flat, permitting the bearings 218 to closely ride within the scalloped 226 top piston surface 220. In contrast, the portion of the bearing body 216 that contacts the surrounding tubular body, e.g., casing, is arcuate. In one aspect, the arcuate surface of the bearing body 216 is also tapered in diameter. The tapered shape allows the expander tool 200 to both rotate and translate within the wellbore simultaneously. In this respect, the expander tool 200 is preferably urged within the wellbore in the direction of the bearing body 216 end having the reduced diameter.

[0049] In the configuration of the bearing body 216 shown in FIG. 4, opening 213 is provided for loading the bearings 218 into the races 214. The opening 213 is disposed on the surface of the bearing body 216 proximate to the piston 220. In one aspect, each race 214 has a bearing opening 213.

[0050] The tapered bearing body 216 and the bearings 218 are fabricated from a material of appreciable strength and toughness in order to withstand the high hertzian stresses imposed during an expansion operation. Preferably, the bearing body 216 and bearings 218 are fabricated from a ceramic or other hardened composite material. Alternatively, a steel or other hard metal alloy may be used. In any arrangement, it is understood that some sacrifice of the material of the bearings 218 may occur due to the very high stresses required to expand a surrounding metal tubular.

[0051] In one aspect, the orientation of the tapered bearing body 216 is skewed relative to the longitudinal center axis of the bore of the expander tool 200. To accomplish this, the recess 214 in the expander tool body 202 is tilted so that the longitudinal axis of the body 216 is out of parallel with the longitudinal axis of the tool 200. Preferably, the angle of skew is only approximately 1.5 degrees. The advantage is that simultaneous rotation and translation of the expander tool 200 allows the body 216 to predominantly roll against the surrounding casing being expanded, without skidding against it. This, in turn, causes the thrust system, i.e., the mechanism for raising or lowering the expander tool 200 within the wellbore, to operate more efficiently.

[0052] It is understood that “skewing” of the bearing body 216 is an optional feature. Further, the degree of tilt of the bearing body 216 is a matter of designer's discretion. In any event, the angle of tilt must be away from the direction of rotation of the tool 200 so as to enable the tool 200 to more freely be translated within the wellbore. By employing such an angle, the body 216 will tend to pull itself into the casing as it is expanded (depending on the direction of ‘skew’ and rotation). This again reduces the thrust load required to push the roller into the casing during translation. Tilting the body 216 further causes the body 216 to gain an increased projected depth to expand the casing. This is true for both parallel and tapered rollers.

[0053]FIG. 5 presents a top view of the expansion assembly of FIG. 3. In this view, the configuration of the bearing body 216, and the disposition of the bearing body 216 upon the top surface of the piston 220 can be more fully seen. The preferred tapered configuration of the bearing body 216 is also more fully demonstrated.

[0054] Referring now to FIG. 6, FIG. 6 presents a perspective view of an expander tool 200 as might be used with the expansion assembly 210 of the FIG. 3. The view in FIG. 6 shows the piston 220, the bearing body 216, the mounting brackets 230, and the connectors 232 in exploded arrangement above a recess 214. A plurality of recesses 214 is fabricated into the body 202 of the expander tool 200.

[0055] The body 202 of the expander tool 200 defines a tubular body. A bore 215 is seen running through the body 202. It is to be observed that the diameter of the bore 215 of the improved expander tool 200 is larger than the diameter of the bore 115 of the previously known expander tool 100, shown in FIG. 1.

[0056] Tubular connector members 225, 235 are shown disposed at either end of the expander tool 200. An upper connector 225 is typically connected to a working string, as will be shown in a later figure. A lower connector 235 may be used for connecting the expander tool 200 to other tools further downhole. Alternatively, connector 235 may simply define a deadhead.

[0057]FIG. 7 presents a cross-sectional view of the expander tool 200 of FIG. 6. The view is taken across line 7-7 of FIG. 6. More visible in this view is the enlarged dimension of the bore 215 permitted by the novel expansion assembly 210 of the present invention.

[0058]FIG. 8 presents a perspective view of an expansion assembly 810 of the present invention, in an alternate embodiment. As with the first embodiment of an expansion assembly 210, the second embodiment 810 is designed to be utilized within an expander tool for expanding a surrounding tubular body (not shown in FIG. 8). The expansion assembly 810 is shown exploded away from of an expander tool 200. The expander tool 200 once again includes a tubular body 202 having a plurality of recesses 214 for receiving the expansion assemblies 810.

[0059]FIG. 9 presents a cross-sectional view of the expander tool 200 of FIG. 8. The view is taken across line 9-9 of FIG. 8. FIG. 9 more clearly shows the bore 215 within the expander tool 200, and the radial placement of the expansion assemblies 810.

[0060] As with the expansion assembly 210 of FIG. 3, the expansion assembly 810 of FIG. 8 includes a piston 820 having a top surface and a bottom surface. A piston recess 823 is also formed around the piston 820 for receiving a seal (not shown). The expansion assembly 810 also includes a bearing body 816 residing upon the top surface of the piston 820. However, unlike the bearing body 216 in the expansion assembly 210 of FIG. 3, the bearing body 816 in the expansion assembly 810 of FIG. 8 is preferably integral to the piston 820. With this design, no separate connectors are required. In such an arrangement, the bearing body 816 is directly fastened or otherwise fabricated into the piston 820, as the mounting arrangement.

[0061] The bearing body 816 is fabricated with a race 814 therein. The race 814 is sized to receive a single, large bearing 818. Further, the bearing 818 is permitted to rotate in any direction within the race 814. The relative configurations of the bearing 818 and of the race 814 are shown in the cross-sectional view of FIGS. 10A and 10B. FIG. 10A is a cross-sectional view of the expansion assembly of FIG. 8, taken across a line perpendicular to the longitudinal axis of the expansion assembly. FIG. 10B is a cross-sectional view of the expansion assembly of FIG. 8, taken across the longitudinal axis of the expansion assembly.

[0062] As can be seen from the cross-sectional views of FIGS. 10A and 10B, the single bearing 818 is loaded into the top of the race 814. During an expansion operation, the bearing 818 engages the inner surface of a surrounding tubular to be expanded. As with the plurality of bearings 218 in the first expansion assembly, the single bearing 818 is fabricated from a material of appreciable strength and toughness such that the high hertzian stresses applied during an expansion operation do not detrimentally deform the bearing 818. An example of such a material is tungsten carbide.

[0063] In addition to the single bearing arrangement shown in FIG. 8, the body 816 may be configured to hold two or more bearings, including bearings of different sizes located at different relative heights on the surface of the body. Such bearings would reside in separate but adjacent races. The smaller race is disposed on the expander tool in the direction of the expansion operation so as to aid expansion.

[0064] In order to demonstrate the operation of an expander tool of the present invention, FIGS. 11-14 have been provided. FIG. 11 provides a cross-sectional view of a wellbore 10. The wellbore 10 is cased with an upper string of casing 25. The upper string of casing 25 has been cemented into a surrounding formation 15 by a slurry of cement 20. The wellbore 10 also includes a lower string of casing 30, sometimes referred to as a “liner.” The lower string of casing 30 has an upper portion 30U which has been positioned in the wellbore 10 at such a depth as to overlap with a lower portion 25L of the upper string of casing 25. It can be seen that the lower string of casing 30 is also cemented into the wellbore 10. A packer 35 is shown schematically in FIG. 11, providing support for the lower string of casing 30 within the upper string of casing 25 before the cement 20 behind the lower sting of casing 25 is cured.

[0065]FIG. 12 presents the wellbore of FIG. 11, with a working string WS being lowered into the wellbore 10. Affixed at the bottom of the working string WS is an expander tool 200. The expander tool 200 includes improved expansion assemblies 210. In this view, the expansion assemblies 210 have not yet been actuated.

[0066] Turning now to FIG. 13, the expander tool 200 has been lowered to a depth within the wellbore 10 adjacent the overlapping strings of casing 25L, 30U. The expansion assemblies 210 of the expander tool 200 have been actuated. In this manner, the upper portion 30U of the lower string of casing 30 can be expanded into frictional engagement with the surrounding lower portion 25L of the upper string of casing 20.

[0067] In order to actuate the expander tool 200, fluid is injected into the working string WS. Fluid under pressure then travels downhole through the working string WS and into the perforated tubular bore 215 of the tool 200. From there, fluid contacts the bottom surfaces of the pistons 220. As hydraulic pressure is increased, fluid forces the pistons 220 outwardly from their respective recesses 214. This, in turn, causes the bodies 216 to make contact with the inner surface of the liner 30L. With a predetermined amount of fluid pressure acting on the piston surface 220, the lower string of expandable liner 30L is expanded past its elastic limits. Fluid exits the expander tool 200 through the bottom connector 235 at the base of the tool 200.

[0068] It will be understood by those of ordinary skill in the art that the working string WS shown in FIGS. 12 and 13 is highly schematic. It is understood that numerous other tools may and commonly are employed in connection with a well completion operation. For example, the lower string of casing 30 would typically be run into the wellbore 10 on the working string WS itself. Other tools would be included on the working string WS and the liner 30, including a cement shoe (not shown) and a wiper plug (also not shown). Numerous other tools to aid in the cementing and expansion operation may also be employed, such as a swivel (not shown) and a collet or dog assembly (not shown) for connecting the working string WS with the liner 30.

[0069]FIG. 14 presents the lower string of casing 30 having been expanded into frictional engagement with the surrounding upper string of casing 25 along a desired length. In this view, the upper portion 30U of the lower string of casing 30 has utility as a polished bore receptacle. Alternatively, a separate polished bore receptacle can be landed into the upper portion 30U of the lower string of casing 30 with greater sealing capability. Further, a larger diameter of tubing (not shown) may be landed into the liner 30 due to the expanded upper portion 30U of the liner 30. It is understood that the depictions in FIGS. 12, 13, and 14 are simply to demonstrate one of numerous uses for an expander tool 200, and to demonstrate the operation of the expansion assembly 210.

[0070] As demonstrated, an improved expansion assembly 210 for an expander tool 200 has been provided. In this respect, the bodies 216 of the expansion apparatus 210 are able to reside in close proximity to the surface of a piston 220. In this way, the shaft of previous embodiments of an expander tool has been removed, and a bearing system has been provided in its place. The entire bearing system can be angled to allow the expansion assembly 210 to be rotated and axially translated simultaneously with lower forces applied against the bearing body 216. In one aspect, no shaft or thrust bearing apparatus is needed. In another aspect, a non-circular bearing body 216 is employed, with the bearing body 216 residing immediately upon the surface of the piston 220. With these features, the expansion assembly components 210 are geometrically reduced, thereby affording a larger inner diameter for the bore 215 of the expander tool 200.

[0071] The above description is provided in the context of a hydraulic expander tool. However, it is understood that the present invention includes expander tools in which the pistons are moveable in response to other radially outward forces, such as mechanical forces. While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. 

1. An expansion assembly for an expander tool for expanding a surrounding tubular body, the expansion assembly being disposed within a recess in the body of the expander tool, and the expander tool having a bore therethrough, the expansion assembly comprising: a piston disposed within the recess of the expander tool, the piston having a bottom surface and a top surface, the bottom surface being exposed to a radially outward force within the bore of the expander tool, and the piston being outwardly extendable from the body of the expander tool within the recess in response to the radially outward force; and a bearing body residing in close proximity to the top surface of the piston, the bearing body having at least one race for receiving at least one bearing for engaging the surrounding tubular body when the piston is extended away from the body of the expander tool.
 2. The expansion assembly of claim 1, wherein the at least one bearing defines a plurality of recirculating bearings.
 3. The expansion assembly of claim 2, wherein the bearing body defines a tapered, non-circular body.
 4. The expansion assembly of claim 3, wherein the bearing body comprises: a first substantially flat surface residing upon the top surface of the piston; and a second arcuate surface above the first substantially flat surface.
 5. The expansion assembly of claim 3, wherein the at least one race defines at least two elongated, non-parallel races.
 6. The expansion assembly of claim 3, wherein the at least one race defines an elongated, non-linear race.
 7. The expansion assembly of claim 3, wherein the at least one race defines at least two substantially linear, substantially parallel races.
 8. The expansion assembly of claim 6, wherein the bearing body is substantially rotationally fixed relative to the top surface of the piston.
 9. The expansion assembly of claim 3, further comprising a mounting arrangement for supporting the bearing body upon the top surface of the piston.
 10. The expansion assembly of claim 9, wherein the mounting arrangement comprises: a first bracket affixed to the top surface of the piston for supporting the bearing body at a first end; and a second bracket affixed to the top surface of the piston for supporting the bearing body at a second opposite end.
 11. The expansion assembly of claim 10, wherein each of the first and second brackets receives a connector for connecting the first and second brackets to the respective first and second opposite ends of the body.
 12. The expansion assembly of claim 11, wherein the connector comprises: a plate secured to the bracket; and a tongue extending from the bracket and received within the bearing body at an end.
 13. The expansion assembly of claim 12, wherein each of the first and second brackets receives a connector for connecting the first and second brackets to the respective first and second opposite ends of the body.
 14. The expansion assembly of claim 13, wherein the connector comprises: a plate secured to the bracket; and a tongue extending from the bracket and received within the bearing body at an end.
 15. The expansion assembly of claim 5, wherein the top surface of the piston comprises a plurality of scallops, each scallop sized and configured to receive the plurality of bearings as they recirculate within the at least two races.
 16. The expansion assembly of claim 3, wherein the orientation of the bearing body is skewed relative to the longitudinal center axis of the bore of the expander tool.
 17. The expansion assembly of claim 3, wherein the radially outward forces are hydraulic forces from within the bore of the expander tool.
 18. The expansion assembly of claim 17, wherein the piston sealingly resides within the recess of the body of the expander.
 19. The expansion assembly of claim 1, wherein: the at least one race comprises a first race and a second adjacent race; and the at least one bearing comprises first and second bearings received within the first and second adjacent races, respectively.
 20. The expansion assembly of claim 19, wherein the first bearing is larger than the second bearing.
 21. The expansion assembly of claim 1, wherein the bearing body comprises one race, and one bearing received within the race.
 22. The expansion assembly of claim 21, wherein the radially outward forces are hydraulic forces from within the bore of the expander tool.
 23. The expansion assembly of claim 22, wherein the bearing body is integral to the piston.
 24. An expansion assembly for a hydraulic expander tool for expanding a surrounding tubular body, the expansion assembly being sealingly disposed within a recess in the body of the expander tool, and the expander tool having a bore therethrough, the expansion assembly comprising: a piston residing within the recess of the expander tool, and being outwardly extendable from the body of the expander tool within the recess in response to hydraulic pressure within the bore of the expander tool, the piston comprising a bottom surface exposed to fluid pressure within the expander tool, and a top surface; a bearing body residing upon the top surface of the piston, the roller having at least one race for receiving at least one bearing that engages a surrounding tubular body when the piston is extended away from the body at the expander tool; and a mounting arrangement for supporting the bearing body upon the top surface of the piston such that the roller is substantially rotationally fixed relative to the top surface of the piston.
 25. The expansion assembly of claim 24, wherein: the bearing body is integral to the piston; the at least one race defines a single race; and the at least one bearing defines a single bearing that rotationally resides within the single race.
 26. The expansion assembly of claim 24, wherein the bearing body defines a tapered eccentric body comprising: a first substantially flat surface residing upon the top surface of the piston; and a second arcuate surface above the first substantially flat surface.
 27. The expansion assembly of claim 26, wherein: the at least one race defines at least two substantially linear, substantially parallel races; the at least one bearing defines a plurality of bearings that recirculate within the races; and the top surface of the piston comprises a plurality of scallops, each scallop sized and configured to receive the plurality of bearings as they recirculate within the at least two races.
 28. The expansion assembly of claim 27, wherein the mounting arrangement comprises: a first bracket affixed to the top surface of the piston for supporting the bearing body at a first end; and a second bracket affixed to the top surface of the piston for supporting the bearing body at a second opposite end.
 29. The expansion assembly of claim 28, wherein the orientation of the bearing body is skewed relative to the longitudinal center axis of the bore of the expander tool.
 30. The expansion assembly of claim 29, wherein each of the first and second brackets receives a connector for connecting the first and second brackets to the respective first and second opposite ends of the roller, the connector comprising: a plate secured to the bracket; and a tongue extending from the bracket and received within the roller at an end.
 31. A method for expanding a tubular body within a hydrocarbon wellbore, comprising the steps of: attaching an expander tool to the lower end of a working string, the expander tool having a body and a plurality of recesses within the body, each recess receiving an expansion assembly, each expansion assembly comprising: a piston disposed within the recess of the expander tool, the piston having a bottom surface and a top surface, the bottom surface being exposed to a radially outward force within the bore of the expander tool, and the piston being outwardly extendable from the body of the expander tool within the recess in response to the radially outward force; a bearing body residing in close proximity to the top surface of the piston, the bearing body having at least one race for receiving at least one bearing that engages the surrounding tubular body when the piston is extended away from the body of the expander tool; and a mounting arrangement for supporting the bearing body upon the top surface of the piston such that the bearing body is substantially rotationally fixed relative to the top surface of the piston; running the working string with the expander tool into a wellbore; and rotating the working string in order to radially expand a section of the surrounding tubular body within the wellbore.
 32. The method for expanding a tubular body within a wellbore of claim 31, wherein the at least one bearing defines a plurality of bearings that recirculate within the races.
 33. The method for expanding a tubular body within a wellbore of claim 32, wherein the bearing body comprises: a first substantially flat surface residing upon the top surface of the piston; and a second arcuate surface above the first substantially flat surface.
 34. The method for expanding a tubular body within a wellbore of claim 33, wherein the mounting arrangement comprises: a first bracket affixed to the top surface of the piston for supporting the roller at a first end; and a second bracket affixed to the top surface of the piston for supporting the roller at a second opposite end.
 35. The method for expanding a tubular body within a wellbore of claim 33, wherein the at least one race defines at least two substantially linear, substantially parallel races.
 36. The method for expanding a tubular body within a wellbore of claim 35, wherein the top surface of the piston comprises a plurality of scallops, each scallop sized and configured to receive the plurality of bearings as they recirculate within the at least two races.
 37. The method for expanding a tubular body within a wellbore of claim 35, wherein the orientation of the roller is skewed relative to the longitudinal center axis of the bore of the expander tool.
 38. The method for expanding a tubular body within a wellbore of claim 35, wherein the radially outward forces are hydraulic forces from within the bore of the expander tool.
 39. The method for expanding a tubular body within a wellbore of claim 31, wherein: the at least one race defines a single race; the at least one bearing defines a single bearing rotationally residing within the single race; and the bearing body is integral to the piston.
 40. The method for expanding a tubular body within a wellbore of claim 31, wherein: the at least one race defines two separate but adjacent races; the at least one bearing defines a single bearing rotationally residing within each of the two respective races; and the bearing body is integral to the piston.
 41. An expander tool for expanding a surrounding tubular body in a wellbore, comprising: a body; at least one radially expandable member; and at least one rotatable member disposed on an outer surface of the expandable member for engaging the surrounding tubular body when the radially extendable member is extended away from the body of the expander tool.
 42. A method of expanding a tubular in a wellbore comprising: running an expander tool into the wellbore to a predetermined location adjacent the tubular to the expander, the expander tool comprising: a body; at least one radially expandable member disposed along the body; and at least one rotatable member disposed on an outer surface of the expandable member; and actuating the expander tool, thereby urging the at least one rotatable member into contact with the surrounding tubular member, thereby expanding the tubular member past its elastic limits. 